Pharmacogenomic (PGx) information is increasingly being incorporated into US Food and Drug Administration-approved drug labels. We reviewed the data source (adults vs. pediatrics) of PGx information in approved drug labels and assessed the suitability of applying adult-derived PGx information and related prescribing recommendations to the care of pediatric patients. We identified 65 drugs with labels containing PGx information and that have also been evaluated in children and found that in the majority of cases (56/65, 86%), the PGx information described was derived from adult studies. The application of PGx information from adults to pediatrics was deemed suitable for 71.4% (n= 40) of the drugs and unclear for 28.6% (n= 16). An ontogeny effect, limited or conflicting data regarding ontogeny of the genetic biomarker, or a difference in the pathophysiology or progression of the adult vs. pediatric disease were the primary reasons for deeming direct application from adults to pediatrics unclear.